Wireless communication networks have become a popular choice for variety of communications needs. In response to these needs, companies have created large wireless communication networks including a large number of wireless base stations within these networks. Typically, these base stations are configured to operate synchronously. In other words, all of the base stations transmit data to wireless communication devices during a given period of time, and all of the base stations receive data from wireless communication devices during a different period of time. In an Institute of Electrical and Electronics Engineers (IEEE) 802.16 (WiMAX) network, base stations transmit data during a downlink sub-frame and receive data during an uplink sub-frame. These sub-frames are separated from each other by a pair of guards. The guards are periods of time where all of the base stations are idle, and allow for propagation of the uplink and downlink sub-frames to occur without interference. Together the uplink and downlink sub-frames and the guards constitute a WiMAX frame.
In order to provide smooth handoffs to a wireless communication device travelling through the network, the base stations are configured such that their areas of coverage overlap. This allows time for a smooth handoff between base stations while the wireless communication device is in the overlap area. Since all of the base stations are transmitting at the same time, if adjacent base stations were to transmit on the same frequency, their transmissions would interfere with each other in the coverage overlap area. In order to prevent this interference between the two base stations having overlapping coverage, typically the base stations are configured to operate at different frequencies, or are otherwise configured to avoid interference.
Due to the limited number of available frequencies, large wireless communication networks must re-use frequencies. Typically, these networks are designed such that base stations using common frequencies are separated from each other by large distances. Since transmitted radio waves rapidly loose power as they travel over a distance, in many cases simply spreading out the base stations sharing frequencies is sufficient to avoid interference. However, in certain cases, distant base stations sharing frequencies may still interfere with each other.